Cardiac mapping and ablation systems

ABSTRACT

A probe for cardiac diagnosis and/or treatment has a catheter tube. The distal end of the catheter tube carries first and second electrode elements. The probe includes a mechanism for steering the first electrode element relative to the second electrode element in multiple directions.

This is a continuation of application Ser. No. 08/934,577, filed Sep.22, 1997 now U.S. Pat. No. 6,233,491, which is a continuation ofapplication Ser. No. 08/574,995, filed Dec. 19, 1995, now abandoned,which is a divisional of application Ser. No. 08/136,218, filed Oct. 14,1993, now U.S. Pat. No. 5,476,495, which is a divisional of applicationSer. No. 08/033,681, filed Mar. 16, 1993, now abandoned.

FIELD OF THE INVENTION

The invention relates to systems and methods for mapping and ablatingthe interior regions of the heart for treatment of cardiac conditions.

BACKGROUND OF THE INVENTION

Physicians make use of catheters today in medical procedures to gainaccess into interior regions of the body to ablate targeted tissueareas. It is important for the physician to be able to carefully andprecisely control the position of the catheter and its emission ofenergy within the body during tissue ablation procedures.

The need for careful and precise control over the catheter is especiallycritical during procedures that ablate tissue within the heart. Theseprocedures, called electrophysiological therapy, are becoming morewidespread for treating cardiac rhythm disturbances.

During these procedures, a physician steers a catheter through a mainvein or artery into the interior region of the heart that is to betreated. The physician then further manipulates a steering mechanism toplace the electrode carried on the distal tip of the catheter intodirect contact with the tissue that is to be ablated. The physiciandirects energy from the electrode through-tissue to an indifferentelectrode (in a uni-polar electrode arrangement) or to an adjacentelectrode (in a bi-polar electrode arrangement) to ablate the tissue andform a lesion.

Cardiac mapping can be used before ablation to locate aberrantconductive pathways within the heart. The aberrant conductive pathwaysconstitute peculiar and life threatening patterns, called dysrhythmias.Mapping identifies regions along these pathways, called foci, which arethen ablated to treat the dysrhythmia.

There is a need for cardiac mapping and ablation systems and proceduresthat can be easily deployed with a minimum of manipulation and effort.

There is also a need for systems and procedures that are capable ofperforming cardiac mapping in tandem with cardiac ablation. Suchmultipurpose systems must also be easily. introduced into the heart.Once deployed, such multipurpose systems also must be capable of mappingand ablating with a minimum of manipulation and effort.

SUMMARY OF THE INVENTION

A principal objective of the invention is to provide improved probes tocarry out cardiac mapping and/or cardiac ablation procedures quickly andaccurately.

Another principal objective of the invention is to provide improvedprobes that integrate mapping and ablation functions.

The invention provides a probe for use within the heart to contactendocardial tissue. The probe includes a catheter tube having a distalend that carries a first electrode element. The probe also includes asecond electrode element on the distal end. The second electrode elementdefines a three-dimensional structure that extends along an axis andthat has an open interior. The probe includes a mechanism for moving thefirst electrode element within the open interior of the second electrodeelement in a first direction along the axis of the second electrodeelement, in a second direction rotating about the axis of the secondelectrode element, and in a third direction normal to the axis of thesecond electrode element.

In a preferred embodiment, the movable first electrode element serves toablate myocardial tissue. The second electrode element independentlyserves to sense electrical activity in endocardial tissue.

Other features and advantages of the inventions are set forth in thefollowing Description and Drawings, as well as in the appended Claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view, with portions fragmented and in section, of anendocardial mapping system that embodies the features of the invention,shown deployed and ready for use inside a heart chamber;

FIG. 2 is a side view of endocardial mapping system shown in FIG. 1,with portions fragmented and in section, showing the electrode-carryingbasket in a collapsed condition before deployment inside the heartchamber;

FIG. 3 is an enlarged side view of the electrode-carrying basket andmovable guide sheath shown in FIG. 2, with portions fragmented and insection, showing the electrode-carrying basket in a collapsed conditionbefore deployment;

FIG. 4 is an enlarged side view of the electrode-carrying basket andmovable guide sheath shown in FIG. 1, with portions fragmented and insection, showing the electrode-carrying basket in a deployed condition;

FIG. 5 is a side view of two splines of the basket, when deployed,showing the arrangement of electrodes on the splines;

FIG. 6 is a section view taken generally along line 6—6 in FIG. 1,showing the interior of the catheter body for the mapping probe;

FIG. 7 is a plan view, with portions fragmented, of the introducer andouter guide sheath being introduced into the vein or artery access sitein the process of forming the system shown in FIG. 1;

FIG. 8 is a plan view of the introducer, the outer guide sheath, and thesteerable catheter being introduced into the access site in the processof forming the system shown in FIG. 1;

FIG. 9 is a plan view of the interior of the handle for the steerablecatheter, partially broken away and in section, showing the mechanismfor steering the distal tip of the catheter body;

FIG. 10 is a side view, with portions fragmented and in section, ofadvancing the steerable catheter body and outer guide sheath into thedesired heart chamber;

FIG. 10A is a plan view of the interior of the hemostatic valve thatsystems embodying features of the invention use, showing the resilientslotted membrane present within the valve;

FIG. 11 is a side view, with portions fragmented and in section, of theguide sheath and the steerable catheter body advanced into thedeployment position within the desired heart region;

FIG. 12 is a side view, with portions fragmented and in section, of themapping probe just before being introduced for advancement within theouter guide sheath, with the hemostat sheath fully forward to enclosethe electrode-carrying basket;

FIG. 13 is a side view, with portions fragmented and in section, of themapping probe being advanced through the hemostatic valve of the outerguide sheath, with the hemostat sheath fully forward to enclose theelectrode-carrying basket;

FIG. 14 is a side view, with portions fragmented and in section, of themapping probe after advancement through the hemostatic valve of theouter guide sheath, with the hemostat sheath pulled back to uncover theelectrode-carrying basket;

FIG. 15 is an enlarged view, with portions in section, of theelectrode-carrying basket deployed inside the heart chamber in use inassociation with a separate ablation probe;

FIG. 16 is an enlarged plan view of an alternative three dimensionalstructure, partially in section, that can be deployed using the systemshown in FIG. 1, in use in association with a separate ablation probe;

FIG. 17 is an enlarged side section view of the structure shown in FIG.16 in a collapsed condition before deployment;

FIG. 18 is an enlarged plan view of an alternative three dimensionalstructure that can be deployed using the system shown in FIG. 1, in usein association with a separate ablation probe;

FIG. 19 is an enlarged side section view of the structure shown in FIG.18 in a collapsed condition before deployment;

FIG. 20 is a perspective view, partially fragmented, of an alternativeembodiment of an outer guide sheath having a preformed complexcurvature;

FIG. 21 is an enlarged plan view, partially in section, of the guidesheath shown in FIG. 20 deployed inside the heart chamber and in use inassociation with a separate steerable ablation probe;

FIG. 22 is a perspective view, partially fragmented, of an alternativeembodiment of an outer guide sheath having a steerable distal tip;

FIG. 23 is an enlarged plan view, partially in section, of the guidesheath shown in FIG. 22 deployed inside the heart chamber and in use inassociation with a separate ablation probe;

FIG. 24 is a plan view, with portions fragmented and in section, of anintegrated mapping and ablation system that embodies the features of theinvention;

FIGS. 25 and 26 are enlarged side elevation views of theelectrode-carrying basket of the mapping probe that the system shown inFIG. 24 uses, showing the range of movement of the steerable ablatingelement carried within the basket;

FIG. 27 is a diagrammatic view of the integrated mapping and ablationsystem shown in FIG. 24;

FIG. 28 is an end elevation view, taken generally along line 28—28 inFIG. 26, of the electrode-carrying basket of the mapping probe that thesystem shown in FIG. 24 uses, showing the range of movement of thesteerable ablating element carried within the basket;

FIG. 29 is an enlarged side section view of the distal end of theelectrode-carrying basket of the mapping probe that the system shown inFIG. 24 uses, showing the basket in a collapsed condition about thesteerable ablating element before deployment;

FIG. 30 is an end section view of the collapsed basket, taken generallyalong line 30—30 in FIG. 29;

FIG. 31 is a side section view of the multiple layer catheter body ofthe mapping probe used in the system shown in FIG. 24;

FIG. 32 is a perspective view of the multiple layers of the catheterbody shown in section in FIG. 31;

FIG. 33 is a view, partially in section, showing the formation of thefirst layer of the multiple layer catheter body shown in FIGS. 31 and32;

FIG. 34 is a view, partially in section, showing the formation of thesecond layer of the multiple layer catheter body shown in FIGS. 31 and32;

FIG. 35 is a view showing the formation of the third layer of themultiple layer catheter body shown in FIGS. 31 and 32;

FIG. 36 is a view showing the formation of the fourth layer of themultiple layer catheter body shown in FIGS. 31 and 32; and

FIGS. 37 and 38 are views showing the formation of the fifth and finallayer of the multiple layer catheter body shown in FIGS. 31 and 32.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows an endocardial mapping system 10 that embodies features ofthe invention, when deployed and ready for use within a selected region12 inside the heart.

The Figures generally show the selected region 12 to be the leftventricle of the heart. However, it should be noted that the heart shownin the Figures is not anatomically accurate. The Figures show the heartin diagrammatic form to demonstrate the features of the invention.

When deployed, the system 10 includes an introducer 14, an outer guidesheath 16, and a mapping probe 18.

As FIG. 1 shows, the introducer 14 establishes access to a vein orartery. The outer guide sheath 16 enters the access through theintroducer 14. The guide sheath 16 extends through the vein or artery toenter the selected heart chamber 12.

Together, the introducer 14 and the outer sheath 16 establish apassageway that guides the mapping probe 18 through the access vein orartery and into the selected heart chamber 12.

The mapping probe 18 has a handle 20 (which FIG. 12 shows in itsentirety), an attached flexible catheter body 22, and a movable hemostatsheath 30 with associated carriage 52.

The distal end of the catheter body 22 carries a three dimensionalstructure 24. In FIG. 1, the structure 24 takes the form of a basket.FIGS. 16 and 18 show alternative structures, which will be described ingreater detail later.

The three dimensional structure of the basket 24 includes an exteriorsurface 27 that encloses an open interior area 25. The basket 24 carriesa three dimensional array of electrodes 26 on its exterior surface 27(see FIG. 4 also).

As FIG. 1 shows, when deployed inside the heart chamber 12, the exteriorsurface 27 of the basket 24 holds the electrodes 26 against theendocardial surface.

When fully deployed, the outer guide sheath 16 holds the catheter body22. The sheath 16 is made from an inert plastic material. In thepreferred embodiment, the sheath 16 is made from a nylon compositematerial.

The sheath 16 has an inner diameter that is greater than the outerdiameter of the catheter body 22. As a result, the sheath 16 can slidealong the catheter body 22.

The proximal end of the sheath 16 includes a handle 17. The handle 17helps the user slide the sheath 16 along the catheter body 22, as thearrows in FIGS. 1 and 2 depict. FIGS. 1 and 2 show the range of sheathmovement.

As FIGS. 2 and 3 show, forward movement of the handle 17 (i.e., towardthe introducer 14) advances the distal end of the slidable sheath 16upon the basket 24, the slidable sheath 16 captures and collapses thebasket 24 (as FIG. 3 also shows in greater detail). In this position,the distal end of the sheath 16 entirely encloses the basket 24.

As FIGS. 1 and 4 show, rearward movement of the handle 17 (i.e., awayfrom the introducer 14) retracts the slidable sheath 16 away from thebasket 24. This removes the compression force. The basket 24 opens toassume a prescribed three dimensional shape.

The basket electrodes 26 record the electrical potentials in myocardialtissue. Connectors 44 on the handle 20 (see FIGS. 12 and 13) attach toan external processor (not shown). The processor derives the activationtimes, the distribution, and the waveforms of the potentials recorded bythe basket electrodes 26.

The basket 24 can be variously constructed. In the illustrated andpreferred embodiment (best shown by FIG. 4), the basket 24 comprises abase member 32 and an end cap 34. Generally flexible splines 36 extendin a circumferentially spaced relationship between the base member 32and the end cap 34.

In the illustrated embodiment, eight splines 36 form the basket 24.However, additional or fewer splines 36 could be used, depending uponapplication.

In this arrangement, the splines 36 are made of a resilient inertmaterial, like Nitinol metal or silicone rubber. The splines 36 areconnected between the base member 32 and the end cap 34 in a resilient,pretensed condition.

The resilient splines 36 bend and conform to the tissue surface theycontact. As FIGS. 2 and 3 show, the splines 36 also collapse into aclosed, compact bundle in response to an external compression force.

In the illustrated embodiment (as FIGS. 4 and 5 best show), each spline36 carries eight electrodes 26. Of course, additional or fewerelectrodes 26 can be used. Furthermore, one or more electrodes 26 canalso be located on the end cap 34.

The electrodes 26 can be arranged in thirty-two bi-polar pairs, or assixty-four uni-polar elements. In the preferred embodiment, theelectrodes 26 are made of platinum or gold plated stainless steel.

A signal wire 38 made from a highly conductive metal, like copper, leadsfrom each electrode 26. The signal wires 38 extend down the associatedspline 36, by the base member 32, and into the catheter body 22. Aninert plastic sheath 40 preferably covers each spline 36 to enclose thesignal wires 38 (see FIGS. 4 and 5). In the preferred embodiment, thesheath 40 is made of polyurethane material.

The eight signal wires 38 for each spline 36 are twisted together toform a common bundle 42. As FIG. 6 shows, the eight common bundle 42are, in turn, passed through the catheter body 22 of the mapping probe18. The common bundles 42 extend within catheter body 22 and into theprobe handle 20.

The sixty-four signal wires 38 are distributed within the probe handle20 to one or more external connectors 44, as FIG. 12 shows. In theillustrated embodiment, each connector contains thirty-two pins toservice thirty-two signal wires. The connectors 44 attach to theexternal processor.

As FIG. 6 shows, the catheter body 22 also includes an inner sleeve thatforms a central lumen 46. The wire bundles 42 are oriented in an equallyspaced array about this lumen 46. In the preferred embodiment, thesleeve of the central lumen 46 is made of a Teflon material.

The proximal end of the central lumen 46 is attached to a flushing port48 that extends outside the handle 20, as FIG. 12 shows. The distal endof the central lumen 46 opens at the base member 32 of the basket 24.Anticoagulant or saline can be introduced through the flushing port 48into the heart chamber 12 that the basket 24 occupies.

In the illustrated and preferred embodiment (as FIG. 5 best shows), afirst region 54 on the proximal end of each spline 36 is free ofelectrodes 26. Likewise, a second region 56 on the distal end of eachspline 36 is also free of electrodes 26. These two fore and aft regions54 and 56 generally fail to make stable surface contact with theendocardial tissue. Therefore, electrodes 26 in these regions may notuniformly provide reliable signals.

The eight electrodes 26 on each spline 36 are arranged in 4 groups ofequally spaced pairs in a third region 58 between the two end regions 54and 56. The third region 58 uniformly makes stable surface contact withthe endocardial tissue, creating reliable signals from the electrodes26.

FIGS. 7 to 14 show the details of introducing the system 10 into theheart chamber 12.

The system 10 includes a steerable catheter 60 (see FIG. 8) tofacilitate the introduction and positioning of the outer guide sheath16.

The catheter 60 directs the introduction of the outer guide sheath 16,which is otherwise free of any onboard steering mechanism. The guidesheath 16, in turn, directs the introduction of the mapping probe 18,which is likewise free of any onboard steering mechanism.

Use of a separate catheter 60 for steering purposes results in asignificant reduction in the overall size of the system components.

If the mapping probe 18 carried its own onboard steering mechanism, thecatheter body 22 would have to be of sufficient size to accommodate it.Typically, this would require a catheter body 22 with a diameter ofabout 12-14 French (one French is 0.33 mm in diameter).

Furthermore, if carried onboard the mapping probe 18, the steeringmechanism would also have to be of sufficient strength to deflect theentire structure of the basket 24 when in a collapsed condition.

According to this aspect of the invention, use of a separate, dedicatedsteerable catheter 60 permits the introduction of the entire system 10through the access vessel and into the heart chamber using an outerguide sheath of about only 10 French. The catheter body 22 of themapping probe 18 can also be significantly smaller, being on the orderof 6 to 8 French. In addition, a smaller steering mechanism can also beused, because only the outer sheath 16 needs to be steered.

As FIG. 7 shows, the introducer 14 has a skin-piercing cannula 62. Thephysician uses the cannula 62 to establish percutaneous access into theselected vein or artery (which is typically the femoral vein or artery).The other end of the introducer 14 includes a conventional hemostaticvalve 64.

The valve 64 includes a resilient slotted membrane 65 (as FIG. 10Ashows). The slotted membrane 65 blocks the outflow of blood and otherfluids from the access. The slot in the membrane 65 yields to permit theintroduction of the outer guide sheath 16 through it. The resilientmembrane 65 conforms about the outer surface of the sheath 16, therebymaintaining a fluid tight seal.

The introducer 14 also includes a flushing port 66 for introducinganticoagulant or other fluid at the access site.

As FIG. 8 shows, the steerable catheter 60 includes a catheter body 68having a steerable tip 70 at its distal end. A handle 72 is attached tothe proximal end of the catheter body 68. The handle 12 encloses asteering mechanism 74 for the distal tip 70.

The steering mechanism 74 can vary. In the illustrated embodiment (seeFIG. 9), the steering mechanism is the one shown in Copending U.S.application Ser. No. 07/789,260, which is incorporated by reference.

As FIG. 9 shows, the steering mechanism 74 of this construction includesa rotating cam wheel 76 within the handle 72. An external steering lever78 rotates the cam wheel. The cam wheel 76 holds the proximal ends ofright and left steering wires 80.

The steering wires 80 extend along the associated left and right sidesurfaces of the cam wheel 76 and through the catheter body 68. Thesteering wires 80 connect to the left and right sides of a resilientbendable wire or spring (not shown) that deflects the steerable distaltip 70 of the catheter body 68.

As FIG. 8 shows, forward movement of the steering lever 80 bends thedistal tip 70 down. Rearward movement of the steering lever 80 rearwardbends the distal tip 70 up. By rotating the handle 70, thereby rotatingthe distal tip 70, and thereafter manipulating the steering lever 80 asrequired, it is possible to maneuver the distal tip 70 virtually in anydirection.

In an alternative arrangement (shown in phantom line view A in FIG. 8),the steerable distal tip 70 can also be bent out of a normal coaxialrelationship with the catheter body 68 using custom shaped wirestiffeners 71. The stiffeners 71 create a pre-formed, complex curveconfiguration. The complex curvature simplifies access todifficult-to-reach locations within the heart, such as the aorticapproach through the left ventricle to the left atrium.

FIGS. 10 and 11 show the details of using the steerable catheter 60 toguide the outer sheath 16 into position.

The outer guide sheath 16 includes an interior bore 82 that receives thesteerable catheter body 68 of the catheter 60. The physician can slidethe outer guide sheath 16 along the steerable body 68 of the catheter60.

The handle 17 of the outer sheath 16 includes a conventional hemostaticvalve 84. The valve 84, like the valve 64, includes a resilient slottedmembrane 65 (as FIG. 10A shows) that blocks the outflow of blood andother fluids. Like the valve 64, the slotted membrane 65 yields topermit the introduction of the body 22 of the mapping probe 18 throughit. At the same time, the membrane 65 conforms about the outer surfaceof the body 22 to maintain a fluid tight seal.

Together, the valves 64 and 84 provide an effective hemostatic systemthat allows a procedure to be performed in a clean and relativelybloodless manner.

In use, the steerable catheter body 68 enters the bore 82 of the guidesheath 16 through the valve 84, as FIG. 10 shows. The handle 17 of theouter sheath 16 also preferably includes a flushing port 28 for theintroduction of an anticoagulant or saline into the interior bore 82.

As FIG. 10 also shows, the physician advances the catheter body 68 andthe outer guide sheath 16 together through the access vein or artery.The physician retains the sheath handle 17 near the catheter handle 72to keep the catheter tip 70 outside the distal end of the outer sheath16. In this way, the physician can operate the steering lever 78 toremotely point and steer the distal end 70 of the catheter body 68 whilejointly advancing the catheter body 68 and guide sheath 16 through theaccess vein or artery.

The physician can observe the progress of the catheter body 68 usingfluoroscopic or ultrasound imaging, or the like. The outer sheath 16 caninclude an radio-opaque compound, such a barium, for this purpose.Alternatively, a radio-opaque marker can be placed at the distal end ofthe outer sheath 16.

This allows the physician to maneuver the catheter body 68 through thevein or artery into the selected interior heart chamber 12, as FIG. 10shows.

As FIG. 11 shows, when the physician locates the distal end 70 of thecatheter body 68 in the desired endocardial chamber 12, he/she slidesthe outer sheath handle 17 forward along the catheter body 68, away fromthe handle 72 and toward the introducer 14. The catheter body 68 directsthe guide sheath 16 fully into the heart chamber 12, coextensive withthe distal tip 70.

Holding the handle 17 of the outer sheath 16, the physician withdrawsthe steerable catheter body 68 from the outer guide sheath 16.

The system 10 is now deployed in the condition generally shown in FIG.12. As FIG. 12 shows, the guide sheath bore 82 establishes a passagewaythat leads directly from the introducer 14 into the selected heartchamber 12. The mapping probe 18 follows this passageway for deploymentinside the chamber 12.

As FIG. 12 shows, before introducing the mapping probe 18, the physicianadvances the hemostat sheath 30, by pushing on the carriage 52. Thesheath 30 captures and collapses the basket 24.

As FIG. 13 shows, the physician introduces the hemostat sheath 30, withenclosed basket 24, through the hemostatic valve 84 of the outer sheathhandle 17. The hemostat sheath 30 protects the basket electrodes 26 fromdamage during insertion through the valve 84.

As FIG. 14 shows, when the catheter body 22 is advanced approximatelythree inches into the guide sheath 16, the physician pulls back on thesheath carriage 52 to withdraw the hemostat sheath 30 from the valve 84.The hemostat valve 84 seals about the catheter body 22. The guide sheath16 now itself encloses the collapsed basket 24.

As FIG. 2 shows, the outer sheath 16 directs the basket 24 of mappingprobe 18 to the desired location inside the heart chamber 12. As FIG. 1shows, the physician then moves the handle 17 rearward. The distal endof the sheath 16 slides back to deploy the basket 24 for use.

Once deployed, the physician can again collapse the basket 24 (bypushing forward on the handle 17), as FIG. 2 shows. The physician canthen rotate the sheath 16 and probe 18 to change the angular orientationof the basket electrodes 26 inside the chamber 12, without contactingand perhaps damaging endocardial tissue. The physician can then redeploythe basket 24 in its new orientation by pulling back on the handle 17,as FIG. 1 shows.

The physician analyses the signals received from the basket electrodes26 to locate likely efficacious sites for ablation.

The physician can now takes steps to ablate the myocardial tissue areaslocated by the basket electrodes 26. The physician can accomplish thisresult by using an electrode to thermally destroy myocardial tissue,either by heating or cooling the tissue. Alternatively, the physiciancan inject a chemical substance that destroys myocardial tissue. Thephysician can use other means for destroying myocardial tissue as well.

The illustrated and preferred embodiment accomplishes ablation by usingan endocardial electrode to emit energy that heats myocardial tissue tothermally destroy it. The energy is transmitted between the endocardialelectrode and an exterior indifferent electrode on the patient.

The type of ablating energy can vary. It can, for example, be radiofrequency energy or microwave energy. The ablating energy heats andthermally destroys the tissue to form a lesion, thereby restoring normalheart rhythm.

Ablating energy can be conveyed to one or more electrodes 26 carried bythe basket 24. In this way, one or more of the sensing electrodes 26 onthe basket 24 can also be used for tissue ablation.

As FIG. 15 shows, an external steerable ablating probe 150 can be usedin association with the basket 24. The physician steers the probe 150under fluoroscopic control to maneuver the ablating element 152 into thebasket 24. Once inside the basket 24, the physician steers the ablatingelement 152 into contact with the tissue region identified by the basketelectrodes 26 as the likely efficacious site for ablation. The physicianthen conveys ablating energy to the element 152.

In this arrangement, the basket 24 serves, not only to identify thelikely ablation sites, but also to stabilize the external ablating probe150 within a confined region within the heart chamber 12.

FIGS. 16 and 17 show an alternative configuration for a threedimensional structure 154 that the mapping probe 18 can carry.

In this embodiment, the structure 154 comprises a single length of inertwire material, such a Nitinol metal wire, preformed into a helicalarray. While the particular shape of the helical array can vary, in theillustrated embodiment, the array has a larger diameter in itsmidsection than on its proximal and distal ends.

As FIG. 16 shows, the structure 154 can be used to stabilize theexternal steerable ablation probe 150 in the same fashion as the basket24 shown in FIG. 15 does.

The structure 154 can also carry electrodes 156, like the basket 24, formapping and/or ablating purposes.

As FIG. 17 shows, the structure 154 can be collapsed in response to anexternal compression force. The distal end of the slidable guide sheath16 provides this compression force to retract and deploy the structure154 inside the selected heart chamber, just like the basket structure24.

FIGS. 18 and 19 show yet another alternative configuration for a threedimensional structure 158 that can be carried by the mapping probe 18.In this embodiment, the structure 158 comprises two independent loops160 and 162 of inert wire material, such a Nitinol metal wire.

The loop 160 nests within the loop 162. The distal ends of the nestedloops 160 and 162 are not joined. Instead, the nested loops 160 and 162are free to flex and bend independently of each other.

In the illustrated configuration, the loops 160 and 162 form rightangles to each other. Of course, other angular relationships can beused. Additional independent loops can also be included to form thestructure 158.

As FIG. 18 shows, the loop structure 158 can be used to stabilize theexternal steerable probe 150 in the same fashion as the structures 24and 154 shown in FIGS. 15 and 16 do.

One or more of the loops 160 and 162 can also carry electrodes 164 formapping and/or ablating purposes.

As the previous structures 24 and 154, the structure 158 can becollapsed in response to an external compression force, as FIG. 19shows. The distal end of the slidable guide sheath 16 provides thiscompression force to retract and deploy the structure 158 inside theselected heart chamber 12.

FIGS. 20 and 21 show an alternative embodiment of a guide sheath 166that can be used in association with the introducer 14 to locate asteerable ablation probe 168 inside the selected heart chamber 12.

Unlike the guide sheath 22, the guide sheath 166 is preformed with amemory that assumes a prescribed complex curvature in the absence of anexternal stretching or compressing force.

FIG. 20 shows in phantom lines the guide sheath 166 in a stretched orcompressed condition, as it would be when being advanced along thesteerable catheter body 68 through the access vein or artery.

Upon entering the less constricted space of the heart chamber 12, asFIG. 21 shows, the sheath 166 assumes its complex curved condition. Thecomplex curve is selected to simplify access to difficult-to-reachlocations within the heart, such as through the inferior vena cava intothe right ventricle, as FIG. 21 shows.

Like the sheath 16, the sheath 166 preferably includes a conventionalhemostatic valve 169 on its proximal end. As previously described, thehemostatic valve 169 includes a resilient slotted membrane to block theoutflow of fluids, while allowing passage of a catheter body.

FIG. 21 shows the sheath 166 in use in association with a steerableablating probe 168, which enters the sheath 166 through the hemostaticvalve 169. The sheath 166, like the sheath 16, guides the probe 168through the access vein or artery into the heart chamber 12.

The complex curvature of the sheath 166 more precisely orients thesteerable ablation probe 168 with respect to the intended ablation sitethan the sheath 16. As FIG. 21 shows, the complex curvature points thedistal end of the sheath 166 in a general orientation toward theintended ablation site. This allows the physician to finally orient theablating element 170 with the intended site using fine steeringadjustments under fluoroscopic control.

The embodiment shown in FIGS. 20 and 21 uses the preformed sheath 166 toprovide relatively coarse steering guidance for the ablation probe 168into the heart chamber 12. The sheath 166 simplifies the task of finalalignment and positioning of the ablating element with respect to theprecise ablation region, which the physician can accomplish using a few,relatively fine remote steering adjustments.

FIGS. 22 and 23 show yet another alternative embodiment of a guidesheath 172 that can be used in association with the introducer 14 tolocate an ablation probe 174 inside the selected heart chamber 12.

In FIGS. 22 and 23, the guide sheath 172 includes a sheath body 176 witha steerable distal tip 178. As FIG. 22 shows, the sheath body 176 isextruded to include a center guide lumen 180 and two side lumens 182.Steering wires 183 extend through the side lumens 182, which are locatednear the exterior surface of the body 176.

The distal ends of the steering wires 183 are attached to the sidelumens 182 at the distal tip 178 of the sheath body 176. The proximalends of the steering wires 183 are attached to a steering mechanism 186within a handle 188 attached at the proximal end of the sheath body 176.

The steering mechanism 186 can vary. In the illustrated embodiment, themechanism 186 is the rotating cam arrangement shown in FIG. 9. In thisarrangement, the steering mechanism 186 includes an exterior steeringlever 190. Fore and aft movement of the steering lever 190 deflects thedistal tip 178 of the guide sheath 176, as FIG. 22 shows.

Like the sheath 16, the sheath 172 preferably includes a conventionalhemostatic valve 185 on its proximal end to block the outflow of fluidswhile allowing the passage of a catheter body.

The steerable guide sheath 172 is used in association with theintroducer 14. The physician steers the guide sheath 172 through theaccess vein or artery and into the selected heart chamber 12 underfluoroscopic control, as FIG. 23 shows. The physician then introducesthe probe 174 through the center guide lumen 180.

In this arrangement, the probe 174 can carry a mapping structure, likethose shown in FIGS. 1; 16; and 18. Alternatively (as FIG. 23 shows),the probe 174 carries an ablating element 192.

Because the guide sheath 174 is itself the catheter body 194 of theprobe 174 need not include a steering mechanism. The catheter body 194need only carry the electrical conduction wires its function requires.The catheter body 194 can therefore be downsized. Alternatively, theabsence of a steering mechanism frees space within the catheter body 194for additional or larger electrical conduction wires, as ablatingelements using coaxial cable or temperature sensing elements mayrequire.

FIG. 24 shows an integrated system 86 for performing endocardial mappingand ablation.

Like the first described system 10, the integrated system 86 includes amapping probe 18 with sensing electrodes 26 carried by a threedimensional basket 24. In addition, the integrated system 86 includes,as an integral part, a steerable ablating element 88 that is carriedwithin the open interior area 25 of the basket 24.

The ablating element 88 can be moved relative to the sensing electrodes26 in three principal directions. First, the ablating element 88 movesalong the axis of the mapping probe body 96. Second, the ablatingelement 88 moves rotationally about the axis of the mapping probe body96. Third, the ablating element 88 moves in a direction normal to theaxis of the mapping probe body 96. FIGS. 25 to 28 show the range ofmovement the preferred embodiment provides.

Movement of the ablating element 88 does not effect the contact betweenthe sensing electrodes 26 and the endocardial tissue. In other words,the electrodes 26 and the ablating element 88 are capable of makingcontact with endocardial tissue independent of each other.

More specifically, the system 86 includes a steerable ablation catheter90 that is an integral part of the mapping probe 18. The ablationcatheter 90 includes a steering assembly 92 with a steerable distal tip84. The steerable distal tip 84 carries the ablating element 88.

As FIG. 27 shows diagrammatically, the mapping probe 18 includes acatheter body 96 through which the steering assembly 92 of the ablationcatheter 90 passes during use. The proximal end of the catheter body 96communicates with an opening at the rear of the handle 20. The distalend of the catheter body 96 opens into the interior area 25 of thebasket 24. A conventional hemostatic valve 95 is located at thisjunction. As previously described, the valve 95 includes a resilientslotted membrane that blocks the outflow of fluid while allowing thepassage of the steering assembly 92.

The proximal end of the steering assembly 92 of the ablation catheter 90is attached to a handle 98 (as FIG. 24 best shows). By pulling andpushing the handle 98, the physician moves the ablating element 88 alongthe axis of the mapping probe body 96. By rotating the handle 98, thephysician rotates the ablating element 88 about the axis of the mappingprobe body 96.

The handle 98 further encloses a steering mechanism 74 for the tip 84.The steering mechanism 74 for the ablating catheter 90 is the same asthe steering mechanism 74 for the catheter 60 used in the firstdescribed system 10, and thereby shares the same reference number.

As FIG. 27 generally shows, movement of the steering lever 78 forwardbends the distal tip 84, and with it, the ablating element 88, down.Movement of the steering lever 78 rearward bends the distal tip 84, andwith it, the ablating element 88, up.

FIGS. 25 and 26 also show the movement of the distal tip 84 and element88 through the basket 24 between a generally straight configuration(FIG. 25) and a deflected position, placing the ablating element 88 incontact with endocardial tissue (FIG. 26).

By coordinating lateral (i.e., pushing and pulling) movement of thehandle 98 with handle rotation and tip deflection, it is possible tomove the ablating element 88 in virtually any direction normal to theaxis of the catheter body 96, as FIG. 28 shows.

By rotating and moving the handle 98 in these ways, it is possible tomaneuver the ablating element 88 under fluoroscopic control through thebasket 24 into contact with any point of the endocardial surface of thechamber 12. The ablating 88 can be moved through the basket 24 to tissuelocations either in contact with the exterior surface of the basket 24or laying outside the reach of the basket 24 itself.

A cable 100 with an outer insulating sheath is attached to the ablatingelement 88 (see FIGS. 27 and 29). The electrically insulated cable 100extends down the length of the steering assembly 92. The cable 100conveys ablating energy to the element 88.

A plug 102 attached to the proximal end of the cable 100 (see FIGS. 24and 27) extends outside the handle 98 for connection to a source ofablating energy (not shown).

The integrated mapping and ablation system 86 shown in FIG. 24 sharesvarious other components and methodologies with the first describedsystem 10. Elements shared by the two embodiments are given commonreference numbers.

The integrated system 86 uses the same introducer 14 to establish anaccess. It also uses the same outer guide sheath 16 and the samesteerable catheter 60 (with steerable catheter body 68) to position theouter guide sheath 16. The outer sheath 16 is inserted through theintroducer 14 and positioned inside the heart by the steerable catheterbody 68 in the same fashion as earlier described (and as shown in FIGS.10 and 11).

As also earlier described (and as FIG. 2 shows), the mapping probe 18 isguided by the outer sheath 16 into position. The mapping probe 18 in theintegrated system 86 also includes the slidable sheath 16 to enclose anddeploy the basket 24, in the same manner as earlier described. Whenenclosed by the sheath 16, the basket 24 collapses about the distal tip94 and ablating element 88 (as FIGS. 29 and 30 show).

In use, the physician guides the mapping probe 18 with integral ablatingcatheter 90 into position through the outer sheath 16. The physicianthen deploys the basket 24, freeing the ablating element 88 for use, asFIG. 24 shows.

As FIG. 24 shows, the basket structure contacts the surroundingendocardial tissue to hold and stabilize the ablating element 88 in adesired confined region within the heart while the basket electrodes 26provide mapping signals. The ablating element 88 can be remotely steeredto sites identified by the basket electrodes 26 (as FIG. 26 shows).Ablating energy can then be applied to thermally destroy the tissue.

As in the first described embodiment, the basket electrodes 26 can beused for ablation purposes, too.

As FIGS. 31 and 32 show, the catheter body 96 of the mapping probe 18comprises an integral multiple layer structure. In this structure, thesignal wires 38 for the sensing electrodes 26 on the basket 24 areimbedded within the walls of the catheter body 96. This structure freesspace at the interior of catheter body 96 to accommodate passage of thesteering assembly 92.

As FIGS. 31 and 32 show, the catheter body 96 includes a center tube 106made from a plastic material, such as Pebax tubing. The center tube 106has an interior bore 108 of a size that accommodates the steeringassembly 92 of the ablating catheter 90.

The catheter body 96 includes two layers 110 and 112 of copper signalwire 38 (42 gauge) wrapped about the center tube 106. Each copper signalwire 38 carries an outer insulating sheath. In addition, the two layers110 and 112 are separated from each other by an insulation layer 114 ofTeflon plastic or the like. The layer 114 provides an added measure ofinsulation between the wires 38, particularly in regions where pointcontact between the overlapping wire layers 110 and 112 could occur.

In the illustrated embodiment, where the basket 24 has sixty-fourelectrodes, each layer 110 and 112 carries eight groups of four signalwires 38. The signal wires 38 are preferably wound helically along thelength of the catheter body 96.

The catheter body 96 further includes a metalized plastic layer 116(such as metalized polyamide) that surrounds the second layer 112 ofsignal wires 38. The layer 116 protection against electromagneticinterference (EMI). The layer 116 is, in turn, enclosed within an outerplastic tube 118 of a material such as Pebax.

FIGS. 33 to 38 show a process for making the multiple layer catheterbody 96.

As FIG. 33 shows, the center tube 106 is fastened by clamps 124 to amandrel 126. The mandrel 126 is rotated during the assembly process. Inthe illustrated embodiment, the mandrel 126 rotates in a clockwisedirection.

A wire holder 128 dispenses thirty-two shielded signal wires 38 in eightgroups of four each. During the assembly process, the holder 128advances along the axis of the mandrel 126 upon a rotating lead screw130. In the illustrated embodiment, the lead screw 130 is rotatedclockwise to advance the holder 128 from left to right along the axis ofthe rotating mandrel 126.

By synchronizing the rotation of the mandrel 126 with the translation ofthe holder 128, the wire groups dispensed by the holder 128 arehelically wrapped about the center tube 106. This forms the first layer110 of signal wires 38 about the center tube 106.

As FIG. 34 shows, another holder 132 is advanced by the lead screw 130along the axis of the rotating mandrel 126. The holder 132 helicallywraps insulating Teflon plastic tape 134 about the first layer 110 ofsignal wires 38. This forms the added insulating layer 114 of thecatheter body 96.

As FIG. 35 shows, the wire holder 128 is again advanced by the leadscrew 130 along the axis of the rotating mandrel 126, which during thisstep is rotated counterclockwise. The holder 128 dispenses thirty-twoadditional signal wires 38 in eight groups of four each about theinsulating layer 114. The rotating lead screw 130 advances the holder128 from right to left while the mandrel 126 rotates counterclockwise tohelically wrap the second layer 112 of signal wires 38 about theinsulating layer 114, counterwound to the first layer 110.

The counterwinding of the signal wire layers 110 and 112 providesgreater torque transmission for rotating the basket 24 in response torotating the handle 20. While counterwinding is preferred for thisreason, the signal wire layers 110 and 112 can be wrapped in the samedirection.

As FIG. 36 shows, another holder 136 is advanced by the lead screw 130along the axis of the rotating mandrel 126. The holder 136 helicallywraps metalized plastic material 138 about the second wire layer 112,creating the EMI shield layer 116.

As FIG. 37 shows, another holder 140 advanced by the lead screw 130dispenses adhesive 142 upon the metalized layer 116.

As FIG. 38 shows, the outer sleeve 118 is pulled over the adhesive 142to complete the structure of the multiple layer catheter body 96.

Various features of the invention are set forth in the following claims.

What is claimed is:
 1. A method of using a probe assembly within aheart, the comprising the steps of: providing a probe assembly having acatheter body with a distal end, an ablating element integrally attachedto the catheter body and extending distally beyond the distal end of thecatheter body, a support structure integrally attached to the catheterbody and extending distally beyond the distal end about an axis forcontacting surrounding tissue in the heart, and a steering elementintegrally carried by the catheter body and connected to the ablatingelement for moving the ablating element with respect to the supportstructure, introducing the catheter body, ablating element and supportstructure together as an integrated assembly into and advancing itthrough a patient's vasculature with the support element collapsed aboutthe ablating element, bringing the support structure into contact withheart tissue by expanding the support structure about the ablatingelement, bringing the ablating element into contact with heart tissuewhile maintaining contact between the support structure and heart tissueby operating the steering element to move the ablating element intocontact with heart tissue, transmitting ablation energy to the ablatingelement while contacting heart tissue, completely collapsing the supportstructure about the ablating element, and withdrawing the integratedprobe assembly from the patient vasculature while the support structureis completely collapsed about the ablating element.
 2. The method ofclaim 1, wherein the ablating element is adapted to move in a firstdirection along the axis of the support structure, in a second directionrotating about the axis of the support structure, and in a thirddirection normal to the axis of the support structure, and the methodfurther includes the step of moving the ablating element in at least thethree directions.
 3. The method of claim 1, further including at leastone electrode element carried by the support structure operative forsensing electrical activity in the tissue, and the method furtherincludes the step of sensing electrical activity in the tissue with saidat least one electrode element carried by the support structure.
 4. Themethod of claim 1, further including at least one electrode elementcarried by the support structure operative for emitting energy to ablatetissue, and the method further includes the step of emitting energy toablate tissue with said at least one electrode element carried by thesupport structure.
 5. The method of claim 1, further including ahemostatic valve located within the catheter body, and the methodfurther includes the step of preventing the flow of fluid into thecatheter body with the hemostatic valve.
 6. A method of using a probeassembly within a heart, the comprising the steps of: providing a probeassembly having a catheter body with a distal end, an operative elementintegrally attached to the catheter body and extending distally beyondthe distal end of the catheter body, a support structure integrallyattached to the catheter body and extending distally beyond the distalend about an axis for contacting surrounding tissue in the heart, and asteering element integrally carried by the catheter body and connectedto the operative element for moving the operative element with respectto the support structure, introducing the catheter body, operativeelement and support structure together as an integrated assembly intoand advancing it through a patient's vasculature with the supportelement collapsed about the operative element, bringing the supportstructure into contact with heart tissue by expanding the supportstructure about the operative element, operating the steering element tomove the operative element into a desired position relative to hearttissue while maintaining contact between the support structure and theheart tissue, performing an operative step with the operative element,completely collapsing the support structure about the operative element,and withdrawing the integrated probe assembly from the patientvasculature while the support structure is completely collapsed aboutthe operative element.
 7. The method of claim 6, wherein the operativeelement is adapted to move in a first direction along the axis of thesupport structure, in a second direction rotating about the axis of thesupport structure, and in a third direction normal to the axis of thesupport structure, and the method further includes the step of movingthe operative element in at least the three directions.
 8. The method ofclaim 7, further including at least one electrode element carried by thesupport structure operative for sensing electrical activity in thetissue, and the method further includes the step of sensing electricalactivity in the tissue with said at least one electrode element carriedby the support structure.
 9. The method of claim 7, further including atleast one electrode element carried by the support structure operativefor emitting energy to ablate tissue, and the method further includesthe step of emitting energy to ablate tissue with said at least oneelectrode element carried by the support structure.
 10. The method ofclaim 7, further including a hemostatic valve located within thecatheter body, and the method further includes the step of preventingthe flow of fluid into the catheter body with the hemostatic valve.